12V in back seat & Trunk.

There's a thread about a guy that added one on here somewhere. If you aren't able to find it by the time I get home, I'll do a quick search.

 

I did add one shortly after buying the C. I have a picture of it over in the photo section under WD0AFQ. Simple. The little panel on pas side under the seat. It pops off. Drill hole for the socket, fuse it, and wire it to the battery that is right there.
Dan

 

Since the battery is located under the rear seat, anywhere around there should be a good start.

 

A cool thing about the Prius family is it's very easy to make that a 'switched' socket in case you want to make sure whatever you plug into it won't drain your aux battery when the car's off. You don't even have to poke around for an ignition-switched circuit to tap into for switching; you can just make your switch be voltage-driven and connect it right at the battery. The aux battery voltage will be below 13 when the car's off, and a steady 13.8ish whenever the car is READY thanks to the electronic converter. That lets you build a simple circuit that drives a relay. There's more in this post about the one I built for my Gen 1. The physical details of where to conceal it would be different, but the basics should be the same.

A cool product line I've discovered more recently is distribution panels for Anderson Power Pole connectors. I've always thought it was goofy to plug accessories in with clunky things shoved into cig lighter sockets. The Power Poles make a more secure connection in a much smaller package, so you could have a panel with several outlets in the space of one 'lighter' socket. It's easy to crimp PP connectors on your favorite accessories in place of the goofy lighter plug, or use PP-to-lighter adapters (sold on the same site) for things you don't want to modify. Some of the distribution panels include separate fusing per outlet.

-Chap

 

Update: I've found a neat available product that does pretty much exactly what I built this one to do, complete with the improvement: you can set it so that it doesn't turn off right away when you turn the car off, but stays on for up to two hours longer. It monitors the aux battery voltage during that time so it will shut off early if the voltage ever goes below 11.8, so it still makes sure you don't drain the battery.

-Chap

 

ChapmanF, don't buy the ones at Walmart. I have 3 of those and every one drains my batteries. They do not shut off when they are supposed to. Took one back and replaced it so actually I have had 4 of them.
Dan